Maintaining a Balance

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What are enzymes?

They are protein molecules made by living cells, that are responsible for chemical reactions within an organism.

What are catalysts?

Substances that speed up chemical reactions.

What is a substrate?

A molecule in which an enzyme acts upon.

What is an active site?

The part of a molecule in which an enzyme binds to. The active site has a particular shape, for a specific enzyme, giving substrate specificity.

What is substrate specific?

Describes that an enzyme is only suited to one substrate to their corresponding shape. The active site is reciprocally shaped to bind with that enzyme.

What is metabolism?

The sum of chemical processes occurring within the body within a living cell or organism.

What is the role of enzymes?

Acceleration of chemical reactions (can speed up or slow down reactions without changing temp)

Lowering activation energy.

Temperature sensitivity.

PH sensitivity.

Substrate sensitivity.

What is Homeostasis?

Processes by which organisms use to make sure their internal environment is constant.

What are some examples of homeostasis?

Maintaining...

pH of body fluids.

Body temperature.

Blood glucose levels.

Water and salt balances.

Gas in blood.

Cellular activity and energy levels.

Metabolic waste levels; urea, ammonia, carbon dioxide.

Describe how enzymes control organisms.

They increase the rate of reaction. They are able to be reused many times because they are unchanged by reaction. Therefore, we don't need excessive amounts of enzymes.

Why do we have small amounts of enzymes?

Enzymes are unchanged by reaction and thus reusable. Therefore, a large amount of enzymes isn't required.

What does the term, "specificity of enzymes mean"?

An enzyme has an active site. This is specific as this area only allows specific molecules to fit or be compatible with it due to its shape. See lock and key model.

How does the concentration of a substrate affect enzyme activity?

When the substrate concentration increases, so does the rate of enzyme activity.

There are more substrate molecules available to bind to with the active site.

This would eventually result in the saturation of active sites; all active sites are occupied.

Describe the relationship between enzyme activity and temperature.

When the temperature is too low for enzymes (approx 36 degrees) there is not enough energy for enzymes to generate reactions.

When temperature is too high, the enzyme denatures (destructs, as the 3D structure of the enzyme alters and becomes unusable as they can't fit into substrates).

What is the optimum temperature?

The maximum temperature before an enzyme denatures.

How does changing pH of an organism's internal environment impact on the organism?

Enzymes stop working (denature) at extreme changes in pH. Enzymes in the stomach do not work in the small intestine and vice-versa as they are not suited to the different levels of pH and pH varies in these places they're moving through.

Describe two stages of homeostasis.

Detection and response are the two states.

Light is detected by photoreceptor and thus the response in that the pupil dilates.

Lowered temperature is detected by thermoreceptors and thus the response is shivering.

Oxygen is not very soluble in water and so cannot be carried efficiently dissolved in the blood plasma.

Most of the oxygen is carried by haemoglobin in the red blood cells. Thus, the presence of haemoglobin in red blood cells in blood increases the blood's capacity to carry oxygen.

Organisms with blood (containing haemoglobin) are able to deliver oxygen to cells more efficiently than other organisms with blood that has no haemoglobin.

The net effect is that these organisms are more effective operators in a given environment than their competitors. At high altitudes, blood is not able to absorb as much oxygen as at sea level.

The human body adapts to what is effectively oxygen deprivation by initially increasing heart rate, breathing rate, then the number of red blood cells (more haemoglobin), then density of capillaries.

Select two substances found in blood. Identify the form in which they travel in blood.

Salt. Form is ion which include sodium, potassium, calcium and magnesium.

Plasma. Form is liquid.

Describe the structure of arteries.

Thick, elastic and muscular walls

Used to carry oxygen away from the heart.

Elastic rolls allow for the wall to expand and recoil within each heartbeat.

Describe the structure of capillaries.

One cell thick.

This is because they need to be semi-permeable for gas exchange in and out of it.

Branched structure - provides large surface area for gas exchange.

Describe the structure of veins.

In returning blood to the heart they don't need as much muscle but a wider diameter than arteries.

This is because after flowing through arteries, blood flows at low pressure through the veins.

Describe the chemical composition of blood changes as it moves around the body.

Blood completes a systematic circuit low in O2 and high in CO2. After gaining O2 and losing CO2 in the lungs, it travels to the heart.

Explain why it is essential CO2 is removed from the blood.

CO2 is a waste product of metabolism. Excess C02 results in the blood becoming more acidic. CO2 should be removed so the delicate range of pH in which enzymes function is maintained. Furthermore, when the blood is more acidic the haemoglobin unbinds with O2 more often.

Describe two technologies used to measure blood gases and describe when they are used.

Non evasive device that uses infrared beams of light to measure concentrations of respired gases. The amount of light absorbed determines the amount of CO2 present.

This procedure is not used for critically ill patients as the subjects have to be stable in terms of blood and haemoglobin concentration.

Identify the products of donated blood and discuss their uses.

Packaged RBCs are used to increase haemoglobin levels of a patient while not increasing blood volume.

Cryoprecipitated AHF us removed from the plasma by freezing and then slowly thawing the plasma. Patients with haemophilia or inherited coagulation abnormalities use this to control and prevent bleeding.

Report progress of artificial blood.

Good,

Useful because it is accepted universally.

Costly

No need to refrigerate.

However,

Can only be used to carry O2 or CO2.They are not capable in coagulation or immune defence.More research should be undertaken to gain a better understanding and improve these areas.

Collects in lymph vessels and returned to blood to regulate blood volume (and blood pressure).

Made in lymph glands.

Contains large number of lymphocytes.

What are substances in mammalian blood? (Lecture 2)

CO2

O2

Lipids

Haemoglobin

What is respiration? (Lecture 2)

The release of energy from glucose.

Carbon Dioxide: (Lecture 2)

Toxic waste product of respiration.

Diffuses into blood from cells (from high concentration to low concentration in blood)

Most is converted into hydrogen carbonate ions in red blood cells and moved to plasma (70%).

23% binds to haemoglobin to form carbaminohaemoglobin.

7% dissolved in plasma.

Travels to lungs where it diffuses across respiratory surface (from high concentration to low concentration in the lungs) and expelled into external environment.

Oxygen: (Lecture 2)

Transported as oxyhaemoglobin in red blood cells.

Transported from lungs to cells undergoing respiration.

Water: (Lecture 2)

Solvent of plasma.

Makes up about 60% of total blood volume.

Salts: (Lecture 2)

Dissolved in plasma.

Positive ions include sodium, potassium, calcium and magnesium.

Negative ions include chlorine and hydrogen carbonate.

Lipids: (Lecture 2)

Once digested they are:

-->Converted to triglycerides

--> then packaged with phospholipids and cholesterol

--> released into lymph vessels

--> and then passed into blood and transported to cells for energy for fat tissue (adipose) for storage.

Nitrogenous wastes: (Lecture 2)

Urea, uric acid, creatinine -- transported dissolved in blood plasma.

Transported from body cells to kidney.

Other products of digestion: amino acids, sugars, vitamins.

Haemoglobin: (Lecture 2)

Consists of four polypeptide chains.

Has four active sites where oxygen can bind.

Oxygen binds to the iron.

As one O2 binds, the structure changes to increase the change of another O2 binding. (AN ADAPTIVE ADVANTAGE)

Increases oxygen carrying capacity of blood from 0.2mL/100mL to 20ml/100mL.

The Heart: (Lecture 2)

Muscular pump in double circulation system (on a full circut blood passes through the heart twice).

Mammals -- 4 chambers -- left and right atria, left and right ventricles.

Atria receives blood from veins.

Ventricles pump blood through arteries.

Left and right is separated by septum.

Outline transport systems in plants and what they transport.

Vascular tissue; xylem and phloem.

Transport minerals, and materials.

Dissolved mineral ions from the roots to the leaves.

Xylem:

Xylem: The transpiration-cohesion-tension mechanism is currently the theory that accounts for the ascent of xylem sap. This sap is mainly pulled by transpiration rather than pushed by root pressure. Cohesion is the “sticking” together of water molecules so that they form a continuous stream of molecules extending from the leaves down to the roots. Water molecules also adhere to the cellulose molecules in the walls of the xylem. As water molecules are removed by transpiration in the leaf, the next molecule moves upwards to take its place, pulling the stream of molecules continuously along. This is passive transport.

Phloem:

Phloem: The pressure-flow mechanism (or Source to Sink) is a model for phloem transport now widely accepted.The model has the following steps.Step 1: Sugar is loaded into the phloem tube from the sugar source, e.g. the leaf (active transport)Step 2: Water enters by osmosis due to a high solute concentration in the phloem tube. Water pressure is now raised at this end of the tube.Step 3: At the sugar sink, where sugar is taken to be used or stored, it leaves the phloem tube. Water follows the sugar, leaving by osmosis and thus the water pressure in the tube drops.The building up of pressure at the source end, and the reduction of pressure at the sink end, causes water to flow from source to sink. As sugar is dissolved in the water, it flows at the same rate as the water. Sieve tubes between phloem cells allow the movement of the phloem sap to continue relatively unimpeded.

What is ADH? Where is it made and what does it do?

Made in hypothalamus.

Stored in pituitary.

When the hypothalamus detects an increase in blood concentration, ADH is released.

As a result, tubules that collect water increase in permeability to allow more water to be restored and bring blood concentration back to normal.

If the body required more salt, aldosterone is released so more salt can be absorbed in the tubules.

What are the functions of the kidney?

Excrete wastes from the body.

Achieve homoeostasis by excreting wastes from the body.

Regulate concentrations of salt and water.

What is and when does Addison's disease occur?

Addison disease occurs when the body's immune system attacks the body's own cells and organs.

This is known as an autoimmune disorder.

Occurs mostly in middle ages females; the adrenal cortex is destroyed by the immune system.

This occurs when cortisol and aldosteone are lacking, and is called adrenal insufficiency.

What is the role of aldosterone?

Maintain blood pressure and balance of sodium and potassium in the blood. When there is low aldosterone production, there is too much potassium and not enough sodium. A decrease in sodium may lead to a drop in the amount of fluid in the blood, and thus low blood pressure.

How are deficiencies in aldosterone treated?

Hormone Replacement Therapy: treatment when gland is not producing enough of a hormone.

**fix this question**

When do patients use renal dialysis?

When their kidney function is impaired. They thus require products of metabolism, urea, creatine, uric acid to be removed to stop them from accumulating within the body.

Two types of dialysis?

(1) Peritoneal dialysis: takes place within the body; dialysis solution introduced to the abdominal cavity through the catheter; this abdominal cavity is semi-permeable, so waste and water can pass through.

(2) Disposable collection bag.

How is dialysis similar to kidney function?

The filtration system of the kidney is similar to blood moving through plastic tubing to the dialyser (bundle of permeable fibres) allows wastes to pass through but stops RBC's and platelets so they can be returned to the body.

Describe structure of the mammalian kidney.

Bean shaped.

One million filtering units called nephrons. The top of these are found in the cortex.

Second layer is medulla, holding second part of the nephrons.

Renal artery enters the kidney in branched structure to provide nephrons with blood.

Uterer carries waste out.

Renal vein takes away filtered blood.

Describe the process of filtration in the kidney.

Passively diffuse blood into the glomerulus filtrate.

Occurs in the Bowman's capsule.

Glomerulus - network of capillaries.

Blood pressure is high which forces out substances to the Bowman's capsule.

Non-selective process.

Glomerula filtrate contains some useful substances and some unwanted, useful ones are reabsorbed by the kidney through the process of reabsorption.

Capillary network around nephrons reabsorbs useful substances back into the blood.

Glucose, amino acids, vitamins, minerals, water.

Active process.

Occurs in the loop of Henle and proximal and distal tubules.

Outline the roles of antidiretic hormone and aldosterone in regulating the composition of blood.

Aldosterone is a steroid hormone secreted by the adrenal gland. Its function is to regulate the transfer of sodium and potassium ions in the kidney. When sodium levels are low, aldosterone is released into the blood causing more sodium to pass from the nephron to the blood. Water then flows from the nephron into the blood by osmosis. This results in the homeostatic balance of blood pressure.

Antidiuretic hormone (ADH or vasopressin) controls water reabsorption in the nephron. When levels of fluid in the blood drop, the hypothalamus causes the pituitary to release ADH. This increases the permeability of the collecting ducts to water, allowing more water to be absorbed from the urine into the blood. The resulting urine is more concentrated. When there is too much fluid in the blood, sensors in the heart cause the hypothalamus to reduce the production of ADH in the pituitary, decreasing the amount of water reabsorbed in the kidney. This results in a lower blood volume and larger quantities of more dilute urine.

What is an estuary?

An environment where river meets ocean and fresh water mixes with salt water.

Describe the environment of an estuary.

The estuary environment has a mixture of salt and fresh water, that is constantly fluctuating.

The tide also affects the depth of the water.

As water from the sea and river collide and slow down, sediment settles which provides and abundance of nutrients.

The shallow water allows light to pass through which enables photosynthesis to occur, meaning plans can grow.

It is also an ideal breeding ground for fish and invertebrates, due to warmth, from shallow water and the abundance of nutrients.

What challenges do estuaries pose?

Animals need to be able to adapt to the salinity which is constantly changing. When the tide increases, there is a higher salt concentration.

Other changes occur also that must be adapted to: floods, king tides, droughts.

Using an example describe three main ways plants adapt to environments with high salinity.

Salt exclusion - physiological adaptation where they prevent the entry of salt into their root system by filtration. Passive process that relies on transpiration.

Salt excretion - salt secretors have special glands, usually in their leaves that are able to excrete salt.